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Hurricane Genevieve Discussion Number  12
NWS National Hurricane Center Miami FL       EP122020
300 AM MDT Wed Aug 19 2020

Genevieve continues to have a well-defined eye embedded in a 
central dense overcast with cloud tops temperatures to about -65C.  
The various objective and subjective satellite intensity estimates 
have trended down since the last advisory, and the initial 
intensity is reduced to a possibly generous 100 kt.  Infrared 
imagery hints that the hurricane may be undergoing an eyewall 
replacement cycle.  However, there are no recent microwave data to 
confirm this.

Genevieve continues to move a little more northward than previously 
expected, with the initial motion now north-northwest or 335/9 kt.  
Mid-level ridging to the north and northeast of the hurricane 
should cause a turn toward the northwest during the next 12-24 h, 
with this motion continuing through the balance of the forecast 
period.  The guidance has shifted a little to the east since the 
last advisory, and the new NHC forecast track has been shifted to 
the east of the previous track through 72 h.  The new track keeps 
the center offshore of the Baja California peninsula by 50-60 n mi.

The forecast track takes the center of Genevieve over steadily 
decreasing sea surface temperatures, especially after 12 h.  This 
should cause rapid weakening to begin later today or tonight.  The 
new NHC intensity forecast shows little change in strength during 
the first 12 h due to the chance the hurricane may undergoing an 
eyewall replacement.  After that time, the forecast follows the 
rapid weakening trend of the previous forecast, with Genevieve 
likely to become post-tropical by 96 h and a remnant low by 120 h.  
The new forecast continues to lie above the intensity consensus.

The current forecast track requires a hurricane watch for portions 
of the southern Baja California peninsula at this time.  A 
hurricane warning may be needed if succeeding forecast tracks 
trend closer to the peninsula.
 
Key Messages:
 
1. The center of Genevieve is forecast to move just west of the Baja
California peninsula.  However, the forecast track is now close 
enough to southern Baja California Sur that a Hurricane Watch has 
been issued.  Tropical storm conditions should spread across 
southern Baja California Sur beginning this afternoon and 
continuing through Thursday,
 
2. Large swells generated by Genevieve are affecting portions of the
coast of southern Mexico and will spread northward along the coast
of Mexico to the Baja California peninsula through Thursday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0900Z 20.2N 109.4W  100 KT 115 MPH
 12H  19/1800Z 21.1N 109.9W  100 KT 115 MPH
 24H  20/0600Z 22.1N 110.7W   90 KT 105 MPH
 36H  20/1800Z 22.9N 111.6W   85 KT 100 MPH
 48H  21/0600Z 23.7N 112.7W   75 KT  85 MPH
 60H  21/1800Z 24.7N 114.2W   65 KT  75 MPH
 72H  22/0600Z 25.8N 116.1W   55 KT  65 MPH
 96H  23/0600Z 28.0N 119.5W   35 KT  40 MPH...POST-TROPICAL
120H  24/0600Z 30.0N 122.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Beven
 
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